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8 Sample Configuration
8.1 Analog channels
8.1.1 Voltage input
The formula to convert a measured calculating value
into a physical value is as follows::
=
[phys
..
Value
.]
([
MW
* ]
[
phys
.
FinalValue
=
[
Gradient
]
(
FinalValue
Offset =
M
[
]
[
phys
.
MeasuringV
Description:
[MW]: Current read value across the channel input [V].
[FinalValueMeasuringChannel]: Value at a voltage input
of 10 volts.
Example 1: A sensor having a sensor constant of
10V=1500W/m² ís to be connected to an analog
channel. The final value of the measuring range is 10V.
Accordingly, the gradient is calculated as follows:
1500
W
/
m
=
Gradient
10
If the channel does not show any offset during the
calibration, then 0 can be entered for this channel.
Assuming that the channel has an offset of, e.g.
+15W/m² during calibration, the channel must be set as
follows:
= −15 / ²
Offset
W m
Example 2: A PT100 is to be connected to a channel
via a measuring transducer. At +100°C the measuring
transducer supplies an output voltage of 10V, and at
–50°C it supplies an output voltage of 0V.
This results in the physical final value of measuring
range vs. 150 °C. It follows that the gradient is:
°
150
C
=
=
Gradient
15
10
As the temperature is to be measured up to –50°C,
it follows that the offset is:
= 50
−
°
Offset
C
KACO SOLAR INC.
+
[.
Gradient
..])
[Offset]
−
MeasuringR
ange
MeasuringC
hannel
alue
]
²
=
150
8.1.2 Current Input
The formula to convert the measured calculating value
into a physical value is as follows:
[phys
..
Value
.]
=
[
Gradient
]
(
]
)
Offset =
[
]
[
phys
Explanation:
[MW]: Current measuring value across the channel
input in [mV].
[Final value of measuring scale]: At a current input of
20mA.
8.2 Digital inputs
The conversion to a physical unit is based on the
following equation:
phys
.
MeasuredVa
Example:
A meter supplies 6000 Imp/kWh and is to
be connected to a digital input. This metering constant
is entered directly as a value under "pulse constant"
(Imp./kWh], so that the values already appear
energy values [kWh] on the online display.
To display the current energy reading, a value must be
entered in the field [Interval for current output(s)] , e.g.
60. In this case, the pulses are summed up over a
period of 60 seconds and converted to a mean output
value over the entire interval period.
8.3 Alarm criterion
Another example is used to explain how convenient and
effective plant monitoring can be achieved:
Example:
A photovoltaic installation is equipped with
a radiation sensor to measure the solar radiation
(insolation) at the module level, and with a power
generation meter with pulse output. Based on these
parameters thresholds are to be defined which trigger
an alarm message to report a defect or malfunction
within the plant.
32
Operator's Instructions KACO-proLOG
=
([
MW
* ]
[.
Gradient
...])
−
[
phys
.
FinalValue
MeasuringR
FinalValue
MeasuringC
.
MeasuringV
alue
]
∑
pulses
=
lue
time
.
cons
+
[Offset]
ange
]
)
hannel
tan
t
as
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